Boundary layer energy recovery apparatus

ABSTRACT

Apparatus for recovering thermal energy escaping through a wall structure. The apparatus comprising a wall structure ( 2 ) provided with a thermal energy recovery layer, the thermal energy recovery layer having an arrangement of one or more air breathable sections provided adjacent one or more non-air breathable sections. Rising or falling air ( 3 ) at an outer surface of the wall structure ( 2 ) passes over the one or more non-air breathable sections to collect escaping hot or cold thermal energy before passing through the one or more breathable sections to thereby be recovered. Further provided is an air collection means ( 4 ) for collecting warmed air rising up or cold air flowing down an external wall of said building. The air collection means comprising a tapering converging guide member extending outwardly from the building&#39;s wall ( 2 ) for collecting and directing rising or falling air into the building.

The present invention relates to an apparatus for reclaiming thermalenergy escaping from a body, in particular a building.

Heating, Ventilation and Air Conditioning (HVAC) systems are generallynecessary to maintain a comfortable living environment for occupantswithin enclosed spaces such as homes and public buildings. In temperateclimates such as the UK this is, of course, particularly importantduring the winter months. However, the production and distribution ofheat requires the expenditure of energy, which is often obtained by theburning of fossil fuels. The burning of fossil fuels is well known toproduce various pollutants including carbon dioxide, which is agreenhouse gas linked with the dangers of global warming.

The construction and operation of buildings are together responsible formore than 40% of all primary energy consumption in developed countriessuch as the UK. The emissions from buildings generate more than 50% ofthe UK's annual carbon emissions, commonly known as a “carbonfootprint”. Reducing carbon emissions is widely accepted as critical inthe fight against climate change. It is therefore of importance tominimize the expenditure of energy for maintaining a suitabletemperature within buildings. This would reduce energy costs, lowercarbon emissions and create a more healthy living environment.

Heating systems are commonly used in homes and public buildings. Someheating systems can utilize several local heating units such as gas orelectric fires. Other heating systems can contain a single heating unitwhich is often situated centrally within the building. In these centralheating systems a single boiler, furnace, heat pump or other heatgenerating device acts to heat a fluid medium such as water, steam orair, which is then distributed around the building to various points,for example to a series of radiators. Primarily, radiators act to heat awide body of air within a building through both conduction and alsoconvection, whereby in the latter case a circulation of air is createdby the action of less dense warm air rising through its more densecooler surrounding air. Thus a single radiator can act to heat a widevolume of air as the air circulates around a room.

It is furthermore commonplace for new buildings to contain a form ofinsulation, but there are also many old buildings that contain noinsulation whatsoever. Heat flow through material making up the walls ofa building is determined by the material's resistance to heat flow andthe temperature difference across the material. Thus a heated buildingin winter will conduct heat outwards through the walls, roof and floorto a greater or lesser degree depending upon the temperature differenceand the quality and quantity of insulation.

Traditional insulation is designed primarily to prevent heat loss frominside the building to the outside of the building. Any loss of heat tothe outside of the building is traditionally wasted energy. More energyis expended in order to replace this wasted energy, which leads toincreased carbon emissions or a larger “carbon footprint”. However, notraditional insulation systems of reasonable cost can be 100% effectiveat preventing heat loss from a building to its surrounding environment.

Furthermore, traditional insulation is often combined with measuresdesigned to prevent heat loss that are centred on cutting downinfiltration and ventilation rates—i.e., effectively retaining insidethe building as much air as possible. This can lead to increasedhumidity which can lead to condensation, damp, black spotting, anincreased sensation of stuffiness, and lower general health of theoccupants through “sick building syndrome”. Thus a totally sealedenvironment is generally to be avoided.

The present invention seeks to alleviate the problems associated withthe above.

According to the present invention there is provided apparatus forrecovering thermal energy escaping through a wall structure, saidapparatus comprising: a wall structure provided with a thermal energyrecovery layer, the thermal energy recovery layer having an arrangementof one or more air breathable sections provided adjacent one or morenon-air breathable sections, whereby air at an outer surface of the wallstructure passes over the one or more non-air breathable sections tocollect escaping thermal energy before passing through the one or morebreathable sections to thereby be recovered.

The present invention therefore seeks to compensate for non-existing orimperfect insulation of a building or other body by reclaiming thermalenergy escaping from the exterior of the building or other body anddelivering the reclaimed thermal energy back into the interior of thebuilding or other body. In this respect, the term “thermal energy”includes both hot and cold thermal energy. The present inventiontherefore aims to reduce the extent of traditionally wasted thermalenergy escaping from a building or other body. Thereby the amount ofenergy required to maintain the interior temperature of the building orother body by heating or cooling is minimized and its “carbon footprint”reduced.

The present invention further mitigates heat loss or gain whilst stillallowing a circulation of air between the interior and exterior of abuilding or other body. It therefore allows an effective system ofinsulation which also permits circulation of fresh air into thebuilding, thereby seeking to provide an optimum temperature, humidityand air purity of the interior of a building. Thus the livingenvironment of the interior of the building is maintained a sustainable,energy efficient and healthy environment for the occupants of thebuilding. The breathable sections may take the form of air-permeablemodules which help to cycle warm air into the building during winter orconversely cold air into the building during summer. Moreover, theair-permeable modules may have filtering characteristics for filteringout airborne pollutants from external atmospheric air, thereby, forexample, helping to alleviate symptoms of asthma for occupants.

Preferably, in the case of recovering escaping heat energy, the one ormore air breathable sections are generally vertically elevated withrespect to the one or more non air-breathable sections. In this regard,as the air rises it will naturally pass over the one or more non airbreathable sections and over the one or more air breathable sections.

Conveniently, the wall structure has an outer layer, an outer cavitybeing formed between the outer layer and the heat recovery layer.Preferably, the outer layer has one or more vents for introducing airinto the outer cavity. Such vents are ideally provided at or adjacentthe base of the non air-breathable sections in the wall structure.

Conveniently, the wall structure further comprises an inner layer, aninner cavity being formed between the heat recovery layer and the innerlayer.

Preferably, air drawn in across the recovery layer is collected in theinner cavity and channeled into a structure bounded by the wallstructure.

Conveniently, the apparatus further comprises a converging collectionmember provided at or adjacent the vertical extent of the wallstructure. The converging collection member may take the form of anupturned scoop in cross-section. The collection member may furthermorebe provided as an elongated channel running along the length of the topof the wall structure, for example at the roof line thereof. As such,the collection member is preferably configured to collect air up to 25cm away from the external surface of the outer layer of the wallstructure. The scoop seeks to collect any residual rising air, before itis otherwise lost to the atmosphere over the roof of the building.

Preferably, pressure differential means are provided for establishing apressure differential between opposite sides of the heat recovery layersuch that air is drawn through the breathable sections. Such pressuredifferential means may comprise a Mechanical Ventilation with HeatRecovery unit. Circulation of air from the interior to the exterior of abuilding is beneficial for the well-being of the occupants forreplenishment of oxygen and for preventing excessive humidity within theliving environment.

Conveniently, the air breathable and non-air breathable sections areprovided as modular panels. Preferably, the panels are removable forrepair/replacement. As such, they are versatile and can be used withindifferent construction methods.

Conveniently, the breathable sections have graduated filtering profiles,for progressively filtering air passing therethrough.

According to a further aspect of the present invention there is providedapparatus for recovering heat escaping from a building through a wallstructure, said apparatus comprising:—air collection means forcollecting rising warmed air from an external surface, or boundarylayer, of said wall structure; a main cavity for collecting said risingwarmed air; said main cavity comprising one or more inlets to abreathable insulating filter section, through which said warmed air canpass before being channeled for introduction into said building.

Preferably, the air collection means comprises a converging guide memberprovided at or adjacent the vertical extent of the wall structure. Sucha guide member may be provided at the roof line of a building.

Conveniently, the collection means comprises a wall structureconfiguration having:—an outer layer; a heat recovery layer, and aninner layer, wherein external air is provided to an outer cavity betweenthe outer layer and the heat recovery layer, the heat recovery layerbeing permeable to allow air to pass therethrough to an inner cavitywhich collects and directs air to said main cavity.

In this way, a blanket of tempered outdoor air forms over the heatrecovery layer which has been pre-heated by waste heat through the heatrecovery layer. This tempered air can is then allowed to pass into theinner cavity before being directed to the main cavity.

Preferably, said main cavity is provided in the roof structure of abuilding.

Conveniently, the main cavity is formed between the roof wall and thebreathable insulating filter section.

According to a further aspect of the present invention, there isprovided apparatus for recovering heat escaping from a building, saidapparatus comprising:—

-   -   an air collection means for collecting warmed air rising up an        external wall of said building, said air collection means        comprising a converging guide member for coupling at or adjacent        the building's roof line, the guide member in use extending        outwardly from the building's wall for collecting and directing        rising air into the building.

Embodiments of the present invention will now be described in detail byway of example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view of a conventional house and the heat escapingtherefrom;

FIG. 2 is a schematic view of a house fitted with a heat recoveryapparatus according to a first embodiment of the present invention;

FIG. 3 is a schematic view of a house with a dynamic roof and heatrecovery scoop system according to a second embodiment of the presentinvention;

FIG. 4 is a cross sectional view of a wall section according to thefirst embodiment of the present invention;

FIG. 5 is a partially cut away perspective view of the wall section ofFIG. 4;

FIG. 6 is an enlarged diagram of the roof system of FIG. 3;

FIG. 7 shows the measurement points for the heat scoop effect used inthe experimental test of a third embodiment of the present invention;

FIG. 8 shows the experimental result of the tests conducted on the thirdembodiment shown in FIG. 7 for the week commencing 14 Jan. 2008, withplots of (a) indoor and outdoor temperatures, (b) front and rear heatscoop temperature rises, and (c) median wind speeds; and

FIG. 9 shows the experimental result of the tests conducted on the thirdembodiment shown in FIG. 7 for the week commencing 7 Jul. 2008, withplots of (a) indoor and outdoor temperatures, (b) front and rear heatscoop temperature rises, and (c) median wind speeds,

The embodiments of the present invention described below are for usewith a house, although the present invention can also be applied to anybuilding, such as a school, hospital, residential tower block, officeblock, industrial building, municipal building, etc.

In this respect, FIG. 1 shows a conventional house 1 whose insulation isless than 100% efficient. As such, in winter heat is conducted throughexternal walls 2 to heat the air 3 surrounding the exterior of thebuilding. The warmed air expands, becomes less dense than thesurrounding atmosphere and consequently rises away from the house.Colder air from the surrounding atmosphere moves in to replace the spacearound the house, is itself warmed by conduction of heat through thewalls of the house and also rises away from the house. Thus a cycle ofheating exterior air is created and the energy to drive this cycle iscontinually expelled into the atmosphere and wasted. In summer, asoutdoor temperatures soar, the cycle is reversed and the exterior wallsof the house become relatively cool through conduction with its interiorto thereby cool the air layer that blankets the house. The cool airfalls away from the house, to be replaced by warm outdoor air and so thecycle of coolth loss continues.

FIG. 2 shows a conventional house installed with apparatus of a firstembodiment of the present invention. The air blanket surrounding theexterior of the house is again heated by conduction through the externalwalls of the house as in FIG. 1. The warmed air, which can be up to 7°C. higher in temperature than its surroundings, rises and is collectedby a collection means (heat scoop) 4 which delivers the warm air viasuitable channeling 5 into the interior of the building. Thus, theenergy previously used to heat the air surrounding the external walls,which would have been lost to the atmosphere from a traditional house,is reclaimed back into maintaining the temperature of the interior ofthe house. As less energy is wasted, less energy is required to maintainthe temperature of the house and its carbon footprint is reducedsubstantially. Moreover, abundant fresh air is circulated into the housefrom the outside without cost penalty.

FIG. 4, shows how the wall structure of the house of FIG. 2 has beenenhanced for recovering heat loss. As shown, the wall structurecomprises an outer layer 7 and a heat recovery layer 8. The outer layer7 and heat recovery layer 8 enclose an outer cavity 9, and a vent 10 atthe base of the wall structure allows air to enter into the outercavity. As shown in FIG. 5, air in this cavity flows over non-breathableor static panels 11 and is warmed by heat loss through conduction fromthe interior of the building through the non-breathable panels. The air,thus suitably warmed, will rise through the cavity and pass over thebreathable or dynamic panels 12. The warmed air is drawn through thebreathable or dynamic panels 12 and into an inner cavity 13 is returnedto the recovery layer of the building. The heat recovery layer is formedto incorporate breathable and non breathable sections. The breathablesections are breathable in the sense of dynamically insulated breathablewall technology, namely that they allow air to pass through them at arate compatible with the provision of fresh air ventilation to indoorspaces.

FIGS. 3 and 6 shows a second embodiment of the present invention,comprising the boundary layer recovery heat scoop of the presentinvention together with a dynamic roof apparatus for the purpose ofHeating, Ventilation and Air Conditioning (HVAC). The boundary layerrecovery scoop, and recovery layer in the wall structure again act tocollect the rising warm air surrounding the external walls of thebuilding and channel the warm collected air into a main cavity in theroof of the house. The cavity 15 is formed between an external boundarylayer such as the roof tiles 16 and a series of air permeable orbreathable dynamic “Energyflo™” cells 17. The Energyflo™ cells areconnected to a Mechanical Ventilation with Heat Recovery unit (MVHR) 18as can be seen in FIG. 6, which draws the warm external air into theinterior of the house. The MVHR can also act to extract stale (hot orcold) air from the interior of the house and expel it to the atmosphere.The average temperature in the recovery layer of the dynamic roofarrangement is on average up to 7° C. higher than the outdoor ambienttemperature.

Experimental Example

A third embodiment of the present invention is described below inrelation to FIGS. 7 to 9. This third embodiment is a full-scaleconfidential building trial conducted in the City of Edinburgh,Scotland. The observed experimental performance of the the heat scoopeffect of this third embodiment is summarised below.

The test house featured a dynamically insulated roof, used to supplyfresh, pre-heated, filtered ventilation air to the house via a MVHR unitas shown in FIG. 7. The air intakes were along front and rear eves ofthe roof, directly above the warm blanket of air (the heat recoverylayer) that develops as a result of heat loss through the conventionallyinsulated walls of the house. The incoming air temperatures at theintakes 19,20, outdoor ambient temperature 21, indoor temperature 22 andexternal wind 23,24 (front and sideways components) were continuouslymonitored and recorded over an extended period of 1 year.

The results shown in FIGS. 8 and 9 are for one representative week inwinter (starting 14 Jan. 2008) and one week in summer (starting 7 Jul.2008), respectively. The measure of scoop heat recovery is temperaturerises above ambient. The effect of external wind was considered.

During the winter week the average temperature rise was 3° C. (1.4° C.min to 6.4° C. max) from the rear-facing scoop and 5° C. (2.9° C. min to7.3° C. max) from the front-facing scoop. The average energy recoveredwas around 20% (12% min to 33% max) of the total heat loss through thefront and back walls. The rear scoop appears to be sensitive the normalwind component—see link between (b) and (c) during the second half of15^(th) of January. Also, the evening dip on 18^(th) January confirmsthe relationship between heat loss and indoor to outdoor temperaturedifference—see the link between (a) and (b).

During the summer week the average temperature rise was 4.7° C. (1.2° C.min to 10.9° C. max) from the rear-facing scoop and 5.9° C. (4° C. minto 10.9° C. max) from the front-facing scoop. The average energyrecovered was comparable to that observed for the winter week when thelarge temperature swings attributed to solar gain have been factoredout. The front and rear scoop gains are almost identical and both aresensitive mid-day solar gains—see the multiple links between (a) and (b)throughout the week. The only significant wind during a relatively calmweek, over the 9th and 10th of July, does not appear to have any effect.

During the winter week the house was unoccupied, whereas during thesummer week it was occupied. This is evident from a comparison of theindoor temperature plots in FIGS. 8( a) and 9(a). The variability ofindoor temperatures in the latter is attributed to occupancy.

The above results relate to an non-optimised experimental evaluation ofthe heat scoop effect for a building featuring an exposed heat recoverylayer. From this experimental third embodiment it is expected that, onceoptimised, embodiments of the present will be able to deliver greaterlevels of heat recovery.

The present invention is able to form the basis for a new approach andnew products and applications in both the new and retrofit/refurbishmentbuilding markets and beyond. In this respect, heat scoop of the presentinvention can dramatically improve efficiency in buildings, andparticularly in currently energy inefficient homes and buildings,including the millions of hard to insulate solid wall dwellings inexistence.

It will be understood that the embodiments illustrated above describethe invention in particular forms only for the purposes of illustration.In practice, the invention may be applied to many differentconfigurations, including, but not limited to, building heating andcooling applications, Heating, Ventilation and Air Conditioning (HVAC),fresh air ventilation or any heat recovery application involvingboundary layer heat transfer. The detailed embodiments of which would bestraightforward for those skilled in the art to implement.

For example, in the above illustrative embodiments, the various featuresof the present invention have been described within the context of airbeing heated by the building and rising up the exterior of the building.In such cases, the interior building temperature is higher than theexternal air temperature, as is the case in winter or in colderclimates. Nevertheless, it will also be understood that the presentinvention is equally applicable where the interior building temperatureis lower than the external air temperature, such as in hotter climatesor during the summer. In such cases, with the present invention, thewalls of the building are relatively cool compared to the external airtemperature. This causes the air over the outer surface of the wall tobe cooled, causing it to fall/flow downwardly. The coolth in thisrelatively cool air can then be collected by the present invention andreturned to the interior of the building in order to retain the coolerair temperature indoors. In this way, the present invention is able torecover the coolth or cold flows escaping from the building. This isimportant as significant amounts of energy are often used in order tokeep a building cool, for example by air conditioning units. As such, aswell as the recovery of hot thermal energy described in the aboveembodiments, the present invention is also able to recover cold thermalenergy. The present invention is recovering “thermal energy” in thesense that it is retaining the energy used to cool the interior of thebuilding, or retaining energy which would have otherwise been used tokeep the building cool. As such, the cold thermal energy is embodied inthe coolth or cold flows escaping from the building which aresubsequently recovered by the present invention.

In this connection, in the embodiments of the present invention wherethe wall structure is provided with a heat recovery layer having anarrangement of air breathable sections and adjacent non-air breathablesections, the air at an outer surface of the wall structure passes overthe one or more non-air breathable sections. Here, the air is cooled bythe escaping coolth, which causes it to fall. That is, the relativelycool outer wall surface acts to cool the warmer exterior air. Thedescending cooled air then passes through the one or more breathablesections into the building's interior to thereby recover the coolth.

In other embodiments, an air collection means may be provided having aguide member which extends outwardly from the building's wall andupwardly so as to collect falling cooled air and direct it back into thebuilding. In some embodiments, the air collection means may also enablecollection of both cool and warm air from the outer boundary of theexterior wall. For example, the air collection means may be providedwith two guide members or channels which, respectively, face upwardlyand downwardly so that, depending on conditions, falling cool air orrising hot air can be collected and returned into the building.

Accordingly, it will be understood that embodiments of the presentinvention are therefore able to recover both hot and cold thermalenergy.

1. An apparatus for recovering thermal energy escaping through a wallstructure, said apparatus comprising: a wall structure provided with athermal energy recovery layer, the thermal energy recovery layer havingan arrangement of one or more air breathable sections provided adjacentone or more non-air breathable sections, whereby air at an outer surfaceof the wall structure passes over the one or more non-air breathablesections to collect escaping thermal energy before passing through theone or more breathable sections to thereby be recovered.
 2. Theapparatus according to claim 1, wherein the thermal energy is heat andthe one or more breathable sections are generally vertically elevatedwith respect to the one or more non-breathable sections.
 3. Theapparatus according to claim 1, wherein the wall structure comprises anouter layer, an outer cavity being formed between the outer layer andthe recovery layer.
 4. The apparatus according to claim 3, wherein theouter layer has one or more vents for introducing air into the outercavity.
 5. The apparatus according to claim 1, wherein the wallstructure further comprises an inner layer, an inner cavity being formedbetween the recovery layer and the inner layer.
 6. The apparatusaccording to claim 5, wherein air recovered through the recovery layeris collected in the inner cavity and channeled into a structure boundedby the wall structure.
 7. The apparatus according to claim 1, furthercomprising a converging collection member provided at or adjacent thevertical extent of the wall structure.
 8. The apparatus according toclaim 7, wherein the converging collection member takes the form of anupturned scoop in cross-section.
 9. The apparatus according to claim 7,wherein the converging collection member collects air up to 25 cm fromthe external surface of the outer layer.
 10. (canceled)
 11. Theapparatus according to claim 1, wherein the breathable andnon-breathable sections are provided as panels.
 12. (canceled)
 13. Theapparatus according to claim 1, wherein the breathable sections havegraduated filtering profiles, for progressively filtering air passingtherethrough.
 14. An apparatus for recovering thermal energy escapingfrom a building through a wall structure, said apparatus comprising: aircollection means for collecting rising warmed air or falling cooled airfrom an external surface of said wall structure; a main cavity forcollecting said rising warmed air or falling cooled air from the aircollection means, said main cavity comprising one or more inlets to abreathable insulating filter section through which said warmed or cooledair can pass, before being channeled for introduction into saidbuilding.
 15. (canceled)
 16. The apparatus according to claim 14,wherein the collection means comprises a wall structure configurationhaving: an outer layer; a heat recovery layer, and an inner layer,wherein external air is provided to an outer cavity between the outerlayer and the heat recovery layer, the heat recovery layer beingpermeable to allow air to pass therethrough to an inner cavity whichcollects and directs air to said main cavity.
 17. The apparatusaccording to claim 14, wherein said main cavity is provided in the roofstructure of a building.
 18. The apparatus according to claim 17,wherein the main cavity is formed between the roof wall and thebreathable insulating filter section. 19-20. (canceled)
 21. An apparatusfor recovering a hot or cold air flow resulting from escaping thermalenergy at an outer surface of a building, said apparatus comprising: anair collection means for collecting warmed air rising up, or cooled airflowing down an external wall of said building, said air collectionmeans comprising a tapering converging guide member for coupling at oradjacent the building's external wall, the guide member, in use,extending outwardly from the building's wall for collecting anddirecting rising or falling air into the building.
 22. An apparatus forrecovering thermal energy through a wall structure, said apparatuscomprising: a wall structure provided with an energy recovery layer, theenergy recovery layer having an arrangement of one or more airbreathable sections provided adjacent one or more non-air breathablesections, whereby air at an outer surface of the wall structure passingover the one or more non-air breathable sections is heated or cooledthereby, and then rises or falls before passing through the one or morebreathable sections. 23-24. (canceled)